Among the above-stated sorts of double-folding-type automotive seats, by way of one example, known is a double-folding-type automotive seat with a headrest, which is described in the Laid-Open Patent Publication No. 2010-269622 (Patent-related document 1). This prior-art seat includes: a seat cushion having a forward end portion rotatably mounted on a floor of the automobile; a seat back having a lower end portion rotatably mounted on that floor of the automobile; and a headrest detachably attached to a top of the seat back. When the seat is in normal use for when a seat occupant sits on the seat), the seat back extends upright from a floor of automobile, whereas the seat cushion is set in a horizontally extending state above the floor of automobile. The steps of folding a whole of that seat consist of: rotatively folding the seat cushion upwardly and forwardly relative to the forward end portion thereof to an upright non-use position; then removing the headrest from the top of the seat back, and thereafter, rotatively folding the seat back downwardly and setting the same in a non-use position where it extends horizontally above the floor of automobile. In such double-folded state of the seat, a wide space is given over the folded seat back and can be used as a loading area where baggages can be stored.
According to this conventional seat, during the steps of folding the seat, if the seat back with the headrest attached thereto is folded downwardly, the headrest is inevitably brought to contact with the seat cushion, which makes it hard for a user to smoothly fold the seat back to the non-use position. Thus, to avoid such contact of headrest with the seat cushion, the user first removes the headrest before folding the seat back, and then, after having folded the seat back to the non-use position, he or she places the headrest on a surface of the folded seat back.